This invention relates to a bleach-fix sheet useful in bleaching and fixing an element containing a silver image and a color-providing material so that the resulting element contains only colorant imagewise. The bleach-fix sheet contains a bleach-fix layer or layers comprising a bleaching agent, a fixing agent and a hardened hydrophilic binder, and a water reservoir layer comprising a water-supplying polymer having a water uptake of at least about 30 g water/g polymer.
In the field of rapid access color photography which is directed to the transfer of a colorant imagewise from one layer or element to another receiving layer or element, the color image is provided by a process wherein the colorant or color former is released from a donor layer or element in imagewise fashion and transferred to a receiver layer or element. The image used is the color image in the receiving layer. The donor layer is either removed by peeling or stripping or is retained integrally with the imaged receiver.
Some effort has gone into providing a useful image in photosensitive elements of image-transfer film units. Specifically, the image element, acting as the donor element, comprises a support and one or more silver halide emulsion layers being associated therewith dye image-providing materials, and the receiver element comprises a support containing a dye image-receiving layer. A silver halide developing agent is present in the unit. After the donor element is imagewise-exposed to light, it is brought into contact with a processing composition which causes the colorant or color former to diffuse either in the imaged or non-imaged areas from the donor to the receiver element. The donor element is used by peeling it from the receiving layer and bleaching the silver and fixing the remaining silver halide to leave only colorant or color formers in the imaged or non-imaged areas. Thus, the image used is the retained image in the donor layer or element.
A problem with the above, particularly in instances where the final color image is produced in this initially light-sensitive element, is the need to remove the developed silver image and the residual silver halide. A method employed in the prior art is to bleach and fix the exposed and developed element comprising the bleach-fix sheet as described in Popp et al, U.S. Pat. No. 4,256,826, issued Mar. 17, 1981. This method uses an aqueous alkaline activator solution to activate the retained image process. In most instances, however, particularly in the so-called soak-and-laminate method, an incompletion of the process has been observed. The reactions and transfer of the undesirable by-products to the bleach-fix cover sheet are not complete, resulting in poor image discrimination. It is theorized that the incompletion is a result of not absorbing sufficient activator solution into the laminated structure. This problem is referred to herein as solution starvation.
British Pat. No. 1,330,524 discloses photographic film units wherein a dessicating layer is used to absorb water. The dessicating process is an irreversible removal of water to terminate or slow down a process. The water reservoir layer of the present invention comprising a water-supplying polymer does not irreversibly remove water.
It has been desirable to provide bleach-fix cover sheets which offer improvements in the processing of color photographic materials and improved image discrimination.